Mounting device for disk in spindle motor

ABSTRACT

A spindle motor and a mounting device for mounting a disk in a spindle motor are provided. The mounting device allows for a reduced number of parts, a reduction in product cost, a disk to be smoothly slid and securely mounted to a turntable, and prevents deforming of a disk during mounting. A center guide member is formed of a plastic material, into which the rotating shaft is inserted at an upper end of the turntable, so that it is capable of rising and descending thereon. The center guide member supports the disk. A back yoke is fixed at an upper side of the center guide member on the rotating shaft, to prevent disengaging of the center guide member from the rotating shaft. An outer portion of the center guide member gradually widens toward a lower end thereof, so that the disk can be inserted more securely.

This application is a Continuation of co-pending application Ser. No.11/642,630, filed on Dec. 21, 2006, the entire contents of which arehereby incorporated by reference and for which priority is claimed under35 U.S.C. §120.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a spindle motor, and more particularly,to a mounting device for a disk in a spindle motor.

2. Description of the Related Art

Spindle motors are generally motors installed in optical pick-updevices. A spindle motor rotates a disk so as to read data recorded onthe disk or record data on the disk.

A spindle motor includes a drive unit for spinning a disk and a mountingunit for stably mounting the disk. The present invention relates to amounting device for stably mounting a disk.

In the spindle motor, the drive unit includes a rotor and a stator. Therotor is rotated by an interaction between an electric field generatedby an external power applied to the stator, and a magnetic fieldgenerated from a magnet installed in the rotor. The mounting deviceincludes a first bushing respectively fixed on the stator and rotor fromabove the stator, a turntable fixed on the outer surface of the firstbushing, a center guide member connected to the turntable with a springin between, and a second bushing provided above the center guide member.The spring supports the center guide member from below in vertical andhorizontal directions, and the center of the disk mounted on theturntable is aligned with the rotating axis of the spindle motor forrotating the disk.

Here, spindle motors according to the related art are manufactured withcenter guide members using expensive red brass. Also, the first andsecond bushings connected to the center guide member are alsomanufactured with red brass. Therefore, the material costs formanufacturing the spindle motor are unfavorable.

Additionally, the second bushing and the center guide member aremanufactured separately and coupled together, and a protruding surfacein a stepped shape is formed above and below the boundary of the secondbushing and the center guide member. Accordingly, while the disk isinserted on the second bushing and slid downward in order to load thedisk on the turntable the disk may not be smoothly slide over theboundary surface between the second bushing and the center guide member.

Also, when a disk, made of a resin material, is inserted on the secondbushing and center guide member that are both made of brass, the diskmay be damaged and permanently deformed by the metal.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a spindle motor and amounting device for a disk in a spindle motor that substantiallyobviates one or more problems due to limitations and disadvantages ofthe related art.

An object of the present invention is to provide a spindle motor with areduced number of components and which uses alternative materials toreduce the cost of manufacturing.

Another object of the present invention is to provide a spindle motorthat allows a disk to slide evenly and be mounted on a turntable.

A further object of the present invention is to provide a spindle motorthat does not induce deformation of a disk and facilitates the mountingof a disk.

Additional advantages, objects, and features of the invention will beset forth in part in the description which follows and in part willbecome apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of theinvention. The objectives and other advantages of the invention may berealized and attained by the structure particularly pointed out in thewritten description and claims hereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with thepurpose of the invention, as embodied and broadly described herein,there is provided a spindle motor including: a base; a bearing housingsupported on the base; a bearing provided within the bearing housing; arotating shaft rotatably supported by the bearing; a stator fixed to thebearing housing and wound by at least one coil; a rotor including arotor yoke fixed to the rotating shaft, and a magnet installed on therotor yoke facing the stator; a turntable positioned on the rotor yoke,rotating together with the rotating shaft, and mounting a disk on anupper surface thereof; a center guide member formed of a plasticmaterial, into which the rotating shaft is inserted at an upper side ofthe turntable to be capable of rising and descending thereon, the centerguide member for supporting the disk; an elastic member for elasticallysupporting the center guide member; and a back yoke fixed on therotating shaft at an upper side of the center guide member, forpreventing a disengaging of the center guide member from the rotatingshaft.

In another object of the present invention, there is provided a spindlemotor including: a drive unit providing rotating force for rotating adisk; and a mounting unit for securely mounting the disk, wherein themounting unit includes: a turntable rotating together with a rotatingshaft, for mounting the disk thereon; a center guide member into whichthe rotating shaft is inserted, at an upper side of the turntable, forsupporting the disk; and an elastic member interposed between theturntable and the center guide member, for elastically supporting thecenter guide member from below, wherein the turntable directly contactsand is fixed to the rotating shaft.

In a further object of the present invention, there is provided asupporting structure for a disk in a spindle motor, including: aturntable upon which the disk is mounted; a center guide member formedof a resin material, into which a rotating shaft is inserted at an upperside of the turntable; an elastic member interposed between theturntable and the center guide member, for elastically supporting thecenter guide member; and a back yoke for preventing a disengaging of thecenter guide member.

In a still further object of the present invention, there is provided asupporting structure for a disk in a spindle motor including: aturntable upon which the disk is mounted; a center guide member formedas one body, into which a rotating shaft is inserted, at a upper side ofthe turntable; and an elastic member interposed between the turntableand the center guide member, for elastically supporting the center guidemember, wherein an outer portion of the center guide member is formed toprogressively widen in diameter in a downward direction.

The present invention provides a spindle motor with a reduced number ofcomponents to reduce its manufacturing cost, that allows a disk toevenly slide and be mounted on a turntable, that does not inducedeforming of a disk during its mounting, and that facilitates themounting of a disk thereon.

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings:

FIG. 1 is a sectional view of a spindle motor according to an embodimentof the present invention; and

FIGS. 2 through 4 are respectively a top perspective view, a bottomperspective view, and a sectional view of the center guide member shownin FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts.

FIG. 1 is a sectional view of a spindle motor according to an embodimentof the present invention.

Referring to FIG. 1, the spindle motor 100 according to one embodimentof the present includes a base 200, a bearing housing 110 rising andinstalled on the base 200, a bearing 115 installed within the bearinghousing 110, and a rotating shaft 120 that is rotatably installed withits lower end supported by the bearing 115.

The stator 130 is fixed to the outer surface of the bearing housing 110.The stator 130 includes a core 131 fixed to the outer surface of thebearing housing 110, and coils 135 wound around the core 131.

Also, a rotor 140 is coupled at the proximal center of the rotatingshaft 120 exposed at its top. The rotor 140 is provided in a cylindricalshape open at the bottom, and includes a rotor yoke 141 coupled to theouter surface of the rotating shaft 120, and a magnet 145 coupled to theinner surface of the rotor yoke 141 and facing the stator 130.Accordingly, when a current is supplied to the coils 135,electromagnetic force generated between the stator 130 and the rotor 140rotates the rotor 140, thereby rotating the rotating shaft 120.

The turntable 150 is fixed to the outer surface of the rotating shaft120 at the top of the rotor yoke 141, and a disk 80 is mounted on thetop surface of the turntable 150. Because the turntable 150 is coupleddirectly to the rotating shaft 120, the thickness of the inner surfaceof the turntable 150 contacting the rotating shaft 120 is formed in athickness allowing for a sufficiently strong coupling with the rotatingshaft 120. In the spindle motor 100 according to this embodiment, theinner surface of the turntable 150 contacting the rotating shaft 120 isformed in an elongated tube shape to increase the contacting surfacewith the rotating shaft 120. Selectively, the rotor yoke 141 and theturntable 150 may be fixed together to reinforce the structure.

A center guide member 160, on which the disk 80 is inserted is installedto be capable of rising and descending on the portion of the rotatingshaft 120 that protrudes upward from the turntable 150. For this end, anelastic member 170, such as a spring for elastically supporting thecenter guide member 160 in a radial direction to the rotating shaft 120,is provided between the turntable 150 and the center guide member 160.Therefore, the disk 80 that is inserted and supported on the centerguide member 160 can be mounted on the turntable 150 in a radialdirection to the rotating shaft 120.

The center guide member 160 is injection molded of a plastic material,and includes a coupling plate 161, a dividing wall 163, and a supportingband 165.

FIGS. 2 through 4 are respectively a top perspective view, a bottomperspective view, and a sectional view of the center guide member shownin FIG. 1. With reference to FIGS. 2 through 4, the structure of themounting portion of the spindle motor—especially the center guidemember—will be described in further detail.

Referring to FIGS. 2 through 4, the coupling plate 161 is provided in adisk shape and has an inner surface that is inserted around the outersurface of the rotating shaft 120. The dividing wall 163 extendsannularly upward from a peripheral portion of the coupling plate 161.The supporting band 165 is formed extending downward from an upper endof the dividing wall 163. The disk 80 is inserted and supported thereon.

Here, the supporting band 165 is formed with a gradual slope to beradially more distant from the rotating shaft 120 as it goes from anupper side to a lower side. This is to allow the disk 80 to slide alongthe tapered supporting band 165 and be supported at a lower portionthereof. Also, in order for the disk 80 to evenly slide downward alongthe outer surface of the supporting band 165, the outer surface of thesupporting band 165 may be configured to be smoothly and graduallytapered. This shape may be achieved easily by injection molding thecenter guide member.

Referring to FIGS. 2 through 4, the coupling plate 161 is provided in adisk shape and has an inner surface that is inserted around the outersurface of the rotating shaft 120. The dividing wall 163 extendsannularly upward from a peripheral portion of the coupling plate 161.The supporting band 165 is formed extending downward from an upper endof the dividing wall 163. A space 167 is provided between the supportingband 165 and the dividing wall 163, as shown in FIG. 3. The disk 80 isinserted and supported thereon.

Furthermore, the groove 161 a aids in enabling the center guide member160 to move smoothly about the rotating shaft 120 by minimizing thecontacting surface therewith. The groove 161 a may maintain a uniformclearance between the coupling plate 161 and the rotating shaft 120, sothat movement of the center guide member 160 in a radial direction isminimized. Also, the groove 161 a may contain a lubricant for reducingor dispersing friction between the coupling plate 161 and the rotatingshaft 120.

Referring again to FIG. 1, a back yoke 171 is fixed to the outer surfaceof the upper portion of the rotating shaft 120. The outer surface of theback yoke 171 contacts the inner surface of the dividing wall 163 of thecenter guide member 160. Accordingly, it is prevented that the centerguide member 160 moves with respect to the rotating shaft 120.Especially, movement in a radial direction of the rotating shaft 120 anddisengagement from the rotating shaft 120 are reliably prevented. Here,the back yoke 171 may move in a vertical direction with respect to therotating shaft 120, but may be provided with a catching structure (notshown) for preventing disengagement from the rotating shaft 120.

A magnet 175 may be installed on the back yoke 171. The back yoke 171and the magnet 175 may be fixed each other by a clamp (not shown)descended and aligned with the upper portion of the rotating shaft 120so that the magnet is coplanar with the top of the center guide member160. The clamp presses and clamps the disk 80 mounted on the top surfaceof the turntable 150, and may be fixed while rotating.

Reference number 180 in FIG. 1 is a printed circuit board (PCB).

As described above, the spindle motor according to the present inventionhas a center guide member that is injection molded and thus has a lowermaterial cost compared to the red brass used in the related art.

Also, the center guide member and the turntable are directly coupled tothe rotating shaft, obviating the need for separate components forcoupling the center guide member and the turntable to the rotatingshaft. Thus, the number of components and manufacturing processes arereduced, lowering product cost.

Additionally, the disk can easily slide and mount on the turntable byvirtue of the gradual sloping of the center guide member.

Furthermore, the outer surface of the back yoke fixed to the rotatingshaft contacts the inner surface of the dividing wall of the centerguide member, preventing oscillating of the center guide member withrespect to the rotating shaft, especially in a radial direction to therotating shaft. Accordingly, the center of the center guide member isalways aligned with the center of the rotating shaft, regardless of theinstalled direction of the spindle motor. Thus, the spindle motorinstalled in the optical pick-up device according to the presentinvention allows the optical pick-up device to accurately read data froma disk and accurately record data on a disk.

The present invention may provide other embodiments in accordance withthe scope of the present invention. For example, when the center guidemember can be securely supported on the rotating shaft through the backyoke, there is no need to make the central portion of the center guidemember thicker than the remaining portions thereof, in which case, thereis no need for the groove.

Further, the present invention focuses mainly on the portion of thespindle motor on which the disk is mounted. Therefore, thespecifications of the motor portion consisting of the stator and rotormay change according to the configuration of the spindle motor.

Also, the center guide member has its dividing wall extending upwards,and the supporting band extending downward from around the outside ofthe dividing wall. However, the configuration is not limited thereto,and the dividing wall may extend downward, and the supporting band mayextend upward. In another embodiment, the center guide member is formedof a plastic material for the sake of manufacturing versatility;however, in an alternate embodiment, a plurality of legs that extenddownward may be provided. Of course, because the center guide member isformed of plastic, damage to the disk is prevented.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present invention. Thus,it is intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A spindle motor comprising: a base; a bearing housing supported onthe base; a bearing provided within the bearing housing; a rotatingshaft rotatably supported by the bearing; a stator including a corefixed to the bearing housing and coils wound around the core; a rotorincluding a rotor yoke fixed to the rotating shaft, and a first magnetinstalled on the rotor yoke facing the stator; a turntable positioned onthe rotor yoke, rotating together with the rotating shaft; a centerguide member coupled to the rotating shaft at an upper side of theturntable; an elastic member disposed between the turntable and thecenter guide member for elastically supporting the center guide member,wherein the center guide member comprises: a plate into which therotating shaft is inserted, to be capable of rising and descending; awall formed to extend upward from an outer circumference of the plate;and a band formed to extend downward from the wall, wherein a firstportion of the plate adjacent to the rotating shaft is thicker than asecond portion of the plate adjacent to the wall, wherein the turntableincludes: a first upper surface adjacent to the rotating shaft; a firstwall directly connected to the first upper surface and perpendicular tothe first upper surface; a second upper surface directly connected tothe first wall and perpendicular to the first wall; and a second walldirectly connected to the second upper surface and extended upward, andwherein a lower end of the elastic member is disposed on a boundarybetween the second upper surface and the second wall.
 2. The spindlemotor according to claim 1, wherein the rotor yoke includes a firstportion coupled to the rotating shaft, a second portion connected to anupper portion of the first portion and extended outward in a radialdirection, a third portion connected to the second portion and extendeddownward in a vertical direction, and a fourth portion connected to thethird portion and extended outward in the radial direction, and whereinthe first magnet is disposed on an inner side surface of the thirdportion.
 3. The spindle motor according to claim 2, wherein an uppersurface of the second portion of the rotor yoke includes a first surfaceand a second surface, wherein the first surface is higher than thesecond surface.
 4. The spindle motor according to claim 2, wherein theturntable includes an inner circumferential surface, an outercircumferential surface, and a disk supporting portion disposed at anupper portion of the outer circumferential surface and protruded outwardin the radial direction, and wherein the outer circumferential surfaceis arranged radially between an outer surface of the third portion andan outer surface of the fourth portion.
 5. The spindle motor accordingto claim 1, wherein the elastic member is progressively closer to therotating shaft in an upward direction.
 6. The spindle motor according toclaim 1, wherein the center guide member is formed of a plasticmaterial.
 7. The spindle motor according to claim 1, wherein the centerguide member includes a groove formed around an inner circumference ofthe first portion of the plate.
 8. The spindle motor according to claim1, further comprising: a back yoke fixed on the rotating shaft at anupper side of the center guide member, for preventing a disengaging ofthe center guide member from the rotating shaft.
 9. The spindle motoraccording to claim 8, wherein the back yoke includes a first portion indirect contact with the rotating shaft and a second portion connected tothe first portion of the back yoke and extended outward in the radialdirection.
 10. The spindle motor according to claim 9, wherein the firstportion of the back yoke is thicker than the second portion of the backyoke in the vertical direction.
 11. The spindle motor according to claim8, wherein a top surface of the back yoke is higher than a top surfaceof the rotating shaft.
 12. The spindle motor according to claim 8,further comprising: a second magnet directly coupled to the back yoke.13. The spindle motor according to claim 12, wherein an innercircumferential surface and a lower surface of the second magnet is incontact with the back yoke.
 14. The spindle motor according to claim 13,wherein an outer circumferential surface of the second magnet is incontact with the center guide member.
 15. The spindle motor according toclaim 12, wherein a top surface of the second magnet and a top surfaceof the center guide member are disposed on a same horizontal plane. 16.The spindle motor according to claim 8, wherein a lower surface of theback yoke is partially contacted with an upper surface of the centerguide member.
 17. The spindle motor according to claim 1, wherein alower surface of the turntable is in contact with an upper surface ofthe second portion of the rotor yoke.
 18. The spindle motor according toclaim 12, wherein a lower surface of the second magnet is partiallycontacted with an upper surface of the back yoke.
 19. The spindle motoraccording to claim 1, wherein a portion of the band is spaced from thewall.
 20. The spindle motor according to claim 1, wherein the rotor yokeand the turntable are fixed together.
 21. A spindle motor comprising: abase; a bearing housing supported on the base; a bearing provided withinthe bearing housing; a rotating shaft rotatably supported by thebearing; a stator including a core fixed to the bearing housing andcoils wound around the core; a rotor including a rotor yoke fixed to therotating shaft, and a first magnet installed on the rotor yoke facingthe stator; a turntable positioned on the rotor yoke, rotating togetherwith the rotating shaft; a center guide member directly coupled to therotating shaft at an upper side of the turntable; a back yoke fixed onthe rotating shaft at an upper side of the center guide member, forpreventing a disengaging of the center guide member from the rotatingshaft; a second magnet coupled to the back yoke; and an elastic memberdisposed between the turntable and the center guide member forelastically supporting the center guide member, wherein the elasticmember is progressively closer to the rotating shaft in an upwarddirection, wherein a lower surface of the second magnet is partiallycontacted with an upper surface of the back yoke, wherein an uppersurface of the back yoke includes a recess, wherein the recess faces alower surface of the second magnet, wherein the center guide memberincludes: a plate into which the rotating shaft is inserted, to becapable of rising and descending; a wall formed to extend upward from anouter circumference of the plate to form a first recess to receive theback yoke; and a band formed to extend downward from the wall andprogressively extended farther from a center of the rotating shaft in adownward direction, wherein the plate includes a second recess on anupper surface thereof, and wherein an inner diameter of the secondrecess is spaced from the rotating shaft.
 22. The spindle motoraccording to claim 21, wherein a first portion of the plate adjacent tothe rotating shaft is thicker than a second portion of the plateadjacent to the dividing wall.
 23. The spindle motor according to claim22, wherein the center guide member includes a groove formed around aninner circumference of the first portion of the plate.
 24. The spindlemotor according to claim 23, wherein the groove contains a lubricant.25. The spindle motor according to claim 21, wherein an innercircumferential surface and a lower surface of the second magnet is incontact with the back yoke.
 26. The spindle motor according to claim 21,wherein an outer circumferential surface of the second magnet is incontact with the center guide member.
 27. The spindle motor according toclaim 21, wherein a top surface of the second magnet and a top surfaceof the center guide member are disposed on a same horizontal plane. 28.The spindle motor according to claim 21, wherein a lower surface of theback yoke is partially contacted with an upper surface of the centerguide member.
 29. The spindle motor according to claim 21, wherein therotor yoke and the turntable are fixed together.
 30. A spindle motorcomprising: a base; a bearing housing supported on the base; a bearingprovided within the bearing housing; a rotating shaft rotatablysupported by the bearing; a stator including a core fixed to the bearinghousing and coils wound around the core; a rotor including a rotor yokefixed to the rotating shaft, and a first magnet installed on the rotoryoke facing the stator; a turntable positioned on the rotor yoke,rotating together with the rotating shaft; a center guide member coupledto the rotating shaft at an upper side of the turntable; and an elasticmember disposed between the turntable and the center guide member forelastically supporting the center guide member, wherein the center guidemember comprises: a plate into which the rotating shaft is inserted, tobe capable of rising and descending; a wall formed to extend upward froman outer circumference of the plate; and a band formed to extenddownward from the wall, wherein a first portion of the plate adjacent tothe rotating shaft is thicker than a second portion of the plateadjacent to the wall, wherein an outer circumferential surface of thefirst portion of the plate is closer to the rotating shaft than an outercircumferential surface of a contact portion of the bearing housing,wherein the contact portion of the bearing housing is directly incontact with the core, wherein the turntable includes: an innercircumferential surface; an outer circumferential surface; and a disksupporting portion disposed at an upper portion of the outercircumferential surface and protruded outward in the radial direction,wherein the rotor yoke includes: a first portion coupled to the rotatingshaft; a second portion connected to an upper portion of the firstportion and extended outward in a radial direction; and a third portionconnected to the second portion and extended downward in a verticaldirection, and wherein a vertical distance between a bottom surface ofthe first portion and a top surface of the second portion is greaterthan a vertical length of the inner circumference surface of theturntable.
 31. The spindle motor according to claim 30, wherein thefirst portion and the second portion of the plate are disposed on a samehorizontal plane with a portion of the elastic member.
 32. The spindlemotor according to claim 30, wherein the rotor yoke and the turntableare fixed together.